The potential induced degradation (PID) refers to an output characteristic degradation of certain types of PV panels due to potential induction under a specific voltage relative to the ground. The PID effect will result in a decreased output power of the photovoltaic system.
Therefore, in order to prevent or reduce the PID effect, it is necessary to compensate the voltage of the photovoltaic system relative to the ground, so that bias voltages of the photovoltaic panels relative to the ground are in a range free of the PID effect.
In the conventional art, a voltage compensation apparatus is added on a direct current side of the photovoltaic system. For the photovoltaic system with multiple PV inverters connected in parallel on the alternating current side of the photovoltaic system, the direct side of each of the photovoltaic inverters needs to be added with one such apparatus, resulting in high cost. In addition, a circulating current may exist between the multiple voltage compensation apparatuses, affecting the reliability of the photovoltaic system.
Therefore, it is desired in the field to provide a voltage compensation apparatus for a photovoltaic system which can prevent or reduce the PID effect of photovoltaic panels.